[Warning: work in progress, still in review mode]

Soybean the “cheap protein”

Soy is very cheap to produce1,2 and offers a good amount of proteins3. From a business point of view this is great. From a health and social point of view, you will see later that it is rather a failure.

My opinion on soy

Soy is not a “healthy” food. It is a source of cheap proteins with a good marketing machine behind it. Twelve years ago I studied soy plants and found that it was defending itself very well from insects with the various toxins it could produce. My thought then was that it should not be consumed on the long-term. I was pretty sad hearing people telling me proudly they were drinking soy-milk with health-related considerations.

In the last few years I’ve seen circulating more and more scientific studies indicating that soy was indeed not that healthy, confirming my suspicions. Although the content below will reflect a pretty bad view of soybeans, it is by no mean evil and I wouldn’t be afraid to eat some. But I would not eat it on a regular basis year after year or consider it as a health-food.

Natural plant defenses and toxins in soy

<< The protease inhibitors in soybeans are not only more numerous than those found in other beans and foods, but more resistant to neutralization by cooking and processing. >>5,6Protease inhibitor can be a problem on the long-term.

There is also a toxin in soy called soyatoxin that was found in 1994 and that was found to be highly toxic to mice. The researchers concluded that it is <<important to gather more information concerning its nutritional value, and to develop ways to counteract any detrimental effects. >>7

I could do to same for most plants, and this alone should not be a basis for indicating if it is “healthy” or not. What we need is scientific studies on humans that shows what happens when you eat the whole food (and not just an extracted single-component) over a long period of time. This is what I have gathered in the next sections !

Scientific studies on soy

Brain aging and midlife tofu consumption.<< CONCLUSIONS: In this population, higher midlife tofu consumption was independently associated with indicators of cognitive impairment and brain atrophy in late life. >> http://www.ncbi.nlm.nih.gov/pubmed/10763906

Soy food and isoflavone intake in relation to semen quality parameters among men from an infertility clinic.<< CONCLUSIONS: These data suggest that higher intake of soy foods and soy isoflavones is associated with lower sperm concentration. >>http://www.ncbi.nlm.nih.gov/pubmed/18650557

Bad science in pro-soy articles

Let’s go directly on theSoyfoods Association of North America website in a page where science is supposed to be found, let say in the Men’s health page where there is a lot of references http://www.soyfoods.org/good-for-you-2/mens-health (viewed on August, 2014). It says << Human studies have found that males who consume soy have not had changes in sperm count, sperm quality or sperm motility. >> However if you take the time to look at the fourth reference (Chavarro JE, Toth TL, Sadio SM, Hauser R. Soy food and isoflavone intake in relation to semen quality parameters among men from an infertility clinic. Hum Reprod 2008;23:2584-90.) which talks about semen quality, you will see the following conclusion in the cited study (which is the same study I previously cited in the previous paragraph!!) : << CONCLUSIONS: These data suggest that higher intake of soy foods and soy isoflavones is associated with lower sperm concentration. >>http://www.ncbi.nlm.nih.gov/pubmed/18650557 (Chavarro JE & al).

Be careful about industry-funded articles. In general these tactics could be used :

Reduce the research scope, for example by reducing the length of the study to a few months.

Testing a single nutrient in an in-vitro research, e.g. on isoflavones instead of long-term study of complete soy on human. And than extrapolating (without any scientific data) that the full product is good and should be recommended by health pratitionners.

Extrapolate or distort references, for example by saying something is safe while the reference still shows in the conclusion that more work needs to be done, or like in the example given above about article on the Soyfoods Association of North America website, you can just take a small sentence out of a research and disregard the conclusion. For example a study that says it did not find change in sperm mobility but found that sperm concentration was lower. Then the industry just says that sperm mobility is unchanged “forgets” to mention about the sperm concentration.

Cite other studies made by the industry and camouflage it with a lot of other real scientific studies on facts about your product. Thus having a fresh new scientific paper on the subject that looks authentic. It is like money laundering, but for science paper. One can fund a study, then produce a multiple of articles citing again and again this study along with other real studies.

Soy and cancer

You would need to be pretty wacko to believe that there is a link between cancer and soy. It is a plant from nature that has been eaten for thousands of years and human studies have not found a link between cancer and soy. On the contrary, Asian studies showed that soy was beneficial against cancer. However studies in the US have not shown this beneficial trend. I didn’t find the explanation why, but my hypothesis – for what it is worth – is that either (i) Asians handle soy better and/or (ii) the soy in the US is different. I will add a personal thought that it is time that scientists begin using organic versus non-organic version of food during testing to eliminate the effect of pesticide residues. My source is directly from cancer.org which I believe we can trust to be impartial toward the industry and in the best interest of the fight against cancer :<< (…) a recent study combined data from 14 epidemiologic studies on this topic and found that in Asian countries, women who ate the most (compared to the least) soy isoflavones had a 24% lower risk of developing breast cancer, while there was no association in Western countries such as the U.S. >> and << Bottom line: Even though animal studies have shown mixed effects on breast cancer with soy supplements, studies in humans have not shown harm from eating soy foods. Moderate consumption of soy foods appears safe for both breast cancer survivors and the general population, and may even lower breast cancer risk. Avoid soy supplements until more research is done. So, enjoy your occasional tofu stir-fry or tofu burger – they are unlikely to increase your risk of breast cancer and, on balance, are some of the healthier foods you can eat! >> — http://www.cancer.org/cancer/news/expertvoices/post/2012/08/02/the-bottom-line-on-soy-and-breast-cancer-risk.aspx

How soy is used

Nearly all soybeans are processed for their oil. What remains is high-protein fibers9.

83% of the worldwide production of soy is used to feed animals10.

This means they first extract the oil, then process the rest into protein meal. If you think about it for a minute, that means most of the soy proteins sold on the market have residues from the oil extraction process.

Conclusions

My goal is to tell you that putting the same thing in your diet weeks after weeks, for more than a year is generally not a good idea unless it is really really good – and soybean is not in that category. In fact among all the studies I read I did not read a single thing that would make soybean stand out from a health point of view. It does stand out from an economical point of view and industrial alternative to petroleum in the production of goods. The only good thing I saw was in fermented soybean.

References

1. United States Department of Agriculture, Impacts of Higher Energy Prices on Agriculture and Rural Economies. [Online]. Available from: http://www.ers.usda.gov/media/118256/err123_1_.pdf [Accessed 3rd August 2014]. (Figure 2.1 and 2.2)